The present invention relates to a drilling machine.
A drilling machine of the type under consideration includes an elongated drill pipe driven by a drive positioned outside a borehole being drilled and driving a drill head. Such drilling machines have been utilized for drilling boreholes in rock structures or ground. The drilling machine of the foregoing type has been provided with a support device and water-jet installation by which water is supplied via a descending conduit to the region of the drill head. Water is mixed in that region with the drilled material so that a material-fluid mixture is formed, which is transported via an ascending conduit extending through the drill pipe from the drill head to the borehole mouth.
A drilling machine of the type under discussion has been disclosed for example in DE-PS No. 28 49 245 and "Braunkohle", Heft 7, 1983, page 3. In the drilling machines shown in these disclosure, pressure air is fed in the ascending conduit in accordance with the known air-lifting-drilling process, and an uplift is generated in the conduit. There is an assumption that filling of the borehole with the liquid is the situation which is not acceptable, for example in cases of blind mines and swelling, loose and/or cracked rock.
DE-PS No. 28 49 245 teaches the drilling machine in which a rotatable supporting device which does not serve for supporting a torque of the transmission driven by the drill rod and arranged in the drill head. This device cannot be used for driving a conveying aggregate.
Since the proposed invention relates to the drilling machine for drilling boreholes of large diameters such a machine should be provided with a direct rinsing because otherwise required raising speeds for the material transporting can not be obtained in the borehole. Known hydraulic suction transporting devices require a complete filling of the borehole with the liquid. Pneumatic suction transporting means has the disadvantage which resides in that due to limits by atmospheric air pressure the structure of such pneumatic means is expensive and energy consumption is high.